The overall goal of the proposed project is to increase understanding of the behaviors of young men which are related to HIV and STD transmission and fertility. We focus on testing a new approach to measuring self reported behavior and analyzing changes in sexual activity and contraceptive use across periods of time, across cohorts, and across developmental stages. The proposed work extends our prior research with the National Survey of Adolescent Males (NSAM) project which surveyed a nationally representative household sample of never-married adolescent males ages 15-19 in 1988 and reinterviewed the same respondents in 1991 when they were 2 and on half years older, which has been supported by NICHD. The specific aims of the new project are: 1. To conduct two surveys in 1994: (a) The third wave for the 1988 panel who will be 21-26 years-old and (b) a new panel of 15-19 year old males about:their knowledge and attitudes about AIDS and other STDs, their attitudes about condoms and condom use related to the prevention of pregnancy. AIDS and other STDs, and their levels of sexual activity, experience with partners, and contraceptive use. 2. to develop estimates of levels of sexual activity, condom and other contraceptive use, and other HIV risk behaviors among of 15- 19 year old males in 1994, paralleling data collection for females in the 1994 National Survey of Family Growth Cycle V and adding more depth about behaviors and their determinants. 3. T examine period, age and cohort related changes in attitudes, knowledge, and behaviors regarding sexual activity, partners condoms , other contraception, AIDS and other STDs among young men between 1988, 1991 and 1994. 4. To test whether a new approach to collecting self report data results in increased reporting of stigmatized behaviors by conducting an experiment which randomly assigns members of the new 15-19 year old panel to one of two data collection approaches: (1) Computer Assisted Personal Interview or (2) Personal Interview with Self Administered Questionnaire. 5. To investigate factors influencing the selection of sexual partners on dimensions related to HIV and STD risk, and to investigate longitudinal patterns of partner selection. 6. To examine the association of life transitions (school completion, entry into full time employment, movement out of parental household, and entry into and exit form marriage and cohabitation) with fertility behavior (levels of sexual activity and contraception). 7. To prepare documented public use tapes which will be deposited with the data archive on Adolescent Pregnancy and Pregnancy Prevention at the end of the grant period.